Preheat your oven to 300°F (150°C).
Line a baking sheet with parchment paper and draw a circle (about 8 inches) as a guide. Flip the paper over so the pencil doesn’t touch the meringue.
In a clean, dry bowl, beat the egg whites with an electric mixer on medium speed until soft peaks form.
Gradually add the caster sugar, one tablespoon at a time, beating on high speed. Continue until the mixture is glossy and stiff peaks form. Rub a small amount between your fingers—if it feels gritty, keep beating until the sugar dissolves.
Gently fold in the vinegar, cornstarch, and vanilla extract using a spatula.
Spoon the meringue onto the parchment paper, spreading it within the circle. Create a slight well in the center for the cream and fruit later.
Reduce the oven temperature to 250°F (120°C) and bake for 1 hour. Turn off the oven and let the Pavlova cool completely inside—this prevents cracking.
In a chilled bowl, beat the heavy cream with powdered sugar until soft peaks form.
Transfer the cooled Pavlova to a serving plate. Top with whipped cream and an artistic arrangement of fresh fruit.
Carry it to the table with the flair of a ballerina. Or, if fate has other plans, keep some bowls handy for a quick transformation into Eton Mess.